Update .travis.yml

Author: Aida Torajiro

.travis.yml

@@ -4,6 +4,9 @@ before_cache:
   - rm -f  $HOME/.gradle/caches/modules-2/modules-2.lock
   - rm -fr $HOME/.gradle/caches/*/plugin-resolution/
 
+script:
+  ./gradlew build
+
 cache:
   directories:
     - $HOME/.gradle/caches/